The present invention relates generally to wall panels, and more specifically to acoustical wall panels, such as used as office partitions, and to methods of their fabrication.
It is desirable in many commericial and industrial offices to have a system of modular acoustical dividers that allow privacy while maintaining design flexibility and noise abatement qualities consistent with the desired work environment. To best accomplish these traits it is necessary to produce a panel that consists of a rigid frame, acoustical materials for noise abatement, and an outer decorative cover material for design aesthetics. While it is often desirable to have a soft feel to the exterior of the panel, it is also important to have rigidity across the entire expanse of panel surface so that there is not a great deal of deflection when a force is exerted against the acoustical system within the outer rigid frame. These two traits--soft feel and rigidity for low deflection--can be contradictory in the design of an acoustical system. If the outer surface is soft the inner core must be rigid. Many current panel designs employ a high density fiberglass to achieve rigidity. Others employ a rigid inner septum or barrier of chipboard, metal, wood, or particle board in combination with fiberglass. Both of these approaches are costly with the added cost associated mostly with rigidity in mind.
If either of these approaches are taken to an extreme with too high a density of fiberglass or too thick of a septum material, they can actually detract from the acoustical effectiveness of the design. Rigid materials are often good sound transmitters because they are prone to vibration. As fiberglass insulation increases in density, it becomes a poorer noise absorber of many common sound frequencies found in the office environment. Consider the following results of a standard ASTM test comparing a 3#/cu. ft. density with a 6#/cu. ft. density fiberglass insulation.
______________________________________ Sound Absorption Values Thick- Frequency in Hz ness Density 125 250 500 1000 2000 4000 NRC ______________________________________ 1/2" 3# .10 .39 .34 .54 .74 .86 .50 1/2" 6# .13 .36 .28 .53 .78 .88 .49 ______________________________________
The present invention provides an economical acoustical panel that uses a unique combination of components to achieve improved acoustical performance and to provide the rigidity required for various design specifications. At the same time it can accommodate a range of exterior textures while not compromising acoustical performances or rigidity.
The present invention has a rigid frame of steel, plastic, wood, or other suitable material and has an inner acoustical core with a divider grid defining multiple cells. The core construction has each cell filled with a suitable insulation material such as fiberglass batting or loose, discrete insulation material. A confinement layer may be fastened (stapled, heat sealed, glued) to each surface of the cellular grid to retain the insulation material in the cells. This layering may be a wire screen mesh, plastic mesh, plastic film, cloth, etc. Other features are described in greater detail below.
The present invention provides several significant advantages. The compartmentalized cellular grid is designed to provide the required rigidity. Because the grid comprises mostly open space with each divider grid wall having a minimum of cross-sectional area, it is not as prone to vibrating as is a large, rigid, planar surface when exposed to sound energy. Also, because of the strength provided by this type of geometry, a thin material such as chipboard or other heavy weight paper products can provide rigidity even though these materials are not particularly rigid when a single layer is used in a planar fashion across a frame.
Because of the large percentage of openness in the cellular grid arrangement, the optimum acoustical insulation material may be present in the largest percentage of the panel interior. This material can be chosen for the desired cost/performance combination required regardless of its density or rigidity characteristics.
An additional advantage of this invention is that with the rigidity issue resolved, an intermediate acoustical septum can be located within the core if further noise reduction is desired. This barrier can be of a pliable or viscoelastic nature to abate noise transmission as opposed to a more rigid vibrating member as is used in many existing panel designs.